On July 1st, Toshiba Corporation's Semiconductor Company and Storage Products Company consolidated to form Semiconductor & Storage Products Company.This page describes reliability information of semiconductor products.

Quality and Reliability in Product Development and Design Changes

[As of April, 2011]

Overview

Toshiba semiconductor products are manufactured for a variety of applications, from consumer products to general industrial goods, automobiles. This section describes the system for developing products of high quality and reliability, from product planning to mass production.

Planning

When developing a new semiconductor product, first and foremost sufficient market research must be performed to ensure that the product satisfies customer objectives and the required quality and reliability, and to ensure the product’s general marketability.
System LSI products are classified, according to customer applications, into two groups; general-product and high-reliable product which are graded on quality.
The Sales Department, Application Engineering Department and Quality Assurance Department thoroughly survey the type and actual operating environment of the device in which the product will be used. Circuit conditions, target reliability, design derating, operation conditions and maintenance control are also investigated, in addition to initial functionality and component failure rates. They then determine the specifications for development that incorporate the target reliability and subsequently formulate the development plans.

Development Design

The quality of semiconductor products depends largely on the design.
Product design is based on development specifications carefully studied during the planning phase. Circuit, layout, process and structural designs of sufficient design tolerances are comprehensively considered so as to allow variance in processes and to achieve a design with integrated reliability.
To ensure design quality, a design review is held to deliberate the design from every perspective, confirming factors such as design standards, rules and safety. Design review participants include departments such as Development and Design, Manufacturing Engineering, Application Engineering, and Quality and Reliability. When a problem arises, a design review is conducted.
After the design review, a characteristics evaluation mainly designed to verify target characteristics and functions is performed using trial products, and a design approval test (DAT) is conducted with an emphasis on accelerated testing to verify target quality and reliability under actual use conditions.
DAT results are used to identify design margins and limits. If a defect is discovered, the defect conditions are surveyed and analyzed from every point of view of failure physics to determine the cause, and the results are fed back to the design and manufacturing departments so as to improve quality and reliability.
After completion of the above evaluations, a DAT review meeting is held and, once approval is obtained, the trial production phase is entered.

Trial Production

During the trial production phase, quality and reliability evaluations are conducted to maintain the designed quality and reliability and ensure continued stable production, and a quality approval test (QAT) is conducted to identify process capability, i.e., variations and yields, from the viewpoint of initial flow control.
Based on the evaluation results, the standards used are assessed with respect to appropriateness and information feedback is improved.
Product instructions, QC process charts and other work standards required for production are then prepared, and measurement instruments for manufacturing equipment, jigs and tools are adjusted.
Lastly, a QAT review meeting is held to review the above items and, once approval is obtained, a production transfer meeting is held and the mass production phase is entered.

DR/AT System

Toshiba develops products using the Design Review/Approval Test (DR/AT) system.

Design Review (DR) System

The design review (DR) is a part of the approval test (AT).
At the end of the design phase, a design review is held with the participation of the Development and Design, Manufacturing Engineering, Application Engineering, and Quality and Reliability departments. During the meeting, design standards, design rules (including studies of past incidents), and Contractual Liability/Product Liability (CL/PL) items are confirmed and the evaluation standards that take into consideration the various elements that affect the application, quality and reliability of the trial product are deliberated from various angles, based on departmental knowledge collected using independently developed design review check sheets. In particular, due attention is paid to the confirmation of safety, taking into consideration international safety standards (UL, VDE and others) as well.
The design review results are used as a basis for redesign and for measures such as the addition of AT test items.

Approval Test (AT) System

The approval test (AT) is performed after completion of the design review. First, the engineering grade of the product is assessed and then various evaluations and tests are conducted according to the grade.
Table 1 lists the engineering grades and corresponding AT classifications.
As shown in Table 2 Engineering Grades and Corresponding AT Classifications, the AT system flows, participating departments and evaluation contents are determined according to the AT class.

Table 1 Engineering Grades and Corresponding AT Classifications
Engineering Grade	Technological Novelty	AT Class
I	(1) New technology never before developed domestically or overseas (2) Technology new to Toshiba but already developed by other companies	DAT and QAT
II	(1) Improved conventional technology (2) Existing technology applied to other products	DAT and QAT
II	(3) Change in manufacturing location in the standard product manufacturing phase (4) Change in current manufacturing location during standard product manufacturing phase (5) Subcontracting of a part of the internal process during standard product manufacturing phase	QAT
III	Change made in the standard product manufacturing phase that does not greatly affect the quality and reliability of parts, materials or processes, or the resuming of production after being halted for 12 months or longer	PAT

Supplement
- DAT: Design Approval Test
- QAT: Quality Approval Test
- PAT: Production Approval Test

Reliability testing is also conducted in product family units, such as the design/process family or package family, in order to execute AT effectively. Electrical performance and functionality are particularly evaluated for each product. For further information, refer to Reliability Testing.

Table 2 AT System Overview

This is [Table 2 AT System Overview].

Change Control

Semiconductor products are continually improved so as to enhance performance, decrease size and reduce cost. Changes for such improvements require detailed product evaluation and process control so as to maintain and improve quality and reliability.
The previously described evaluation and design review/approval test (DR/AT) system checks and evaluates improvements and changes, preventing quality problems which may arise in association with such improvements and changes.
If a change or improvement requires modification to product structure, functionality or characteristics, or will have a significant effect on reliability, customer approval is obtained in advance. Toshiba has established the change control system in Figure 1for this purpose.

This is [Figure 1 Product Change Procedure].

Figure 1 Product Change Procedure