JPH02262363A - Manufacture of one chip microcomputer - Google Patents

Abstract

PURPOSE:To reduce the time and cost of a development and allow either one to have the same electric characteristics as well whichever type of a device is developed by making common use of a plurality of photomasks or photomask data in the process in manufacturing of one chip microcomputer with a built-in mask ROM and EPROM. CONSTITUTION:In the process in manufacturing of one chip microcomputers with a built-in mask ROM and EPROM, a plurality of photomasks for photolithography or photomask data are used in common. For example, the form of the mask ROM that is housed in one chip microcomputer with the built-in mask ROM is fitted to a part to be used for one chip microcomputer with the built-in EPROM and further, the layout and sizes of the chip in the mask ROM type and its base circuit structure as well are allowed to have the same configuration as that of the computer with the built-in EPROM. Moreover, in the process of manufacturing, the photomask for photolithography which is used for manufacturing of one chip computer with the built-in EPROM or the photomask date (CAD data and the like) are used in common with the exception of a part of them.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a one-chip microcomputer with a built-in ROM.

[Conventional technology]

ROM usually built into a one-chip microcomputer
There are two types: mask ROII, which captures memory contents during the manufacturing process using a photomask, and electrically writable HF.
There are ROMs etc. However, while mask ROMs are advantageous in terms of cost when mass-producing, they require a long turnaround time, from determining the memory contents to completing a sample.
Moreover, in the case of small-scale production, there is a drawback that the photomask cost becomes high. On the other hand, IEPROM can write the memory contents after manufacturing, which greatly shortens turnaround time and is advantageous in terms of cost. However, wafer processing is complicated, manufacturing costs are high, and mass production is difficult. However, there is a disadvantage in that it is disadvantageous in terms of cost.

In this way, mask ROM and EPROM each have their own advantages.

Due to its disadvantages, in recent years when developing microcomputers, it has become necessary to use a built-in mask ROM type, BPL? Two types of chips with built-in OM are being developed.

By the way, ROM formats used in one-chip microcomputers with a built-in mask ROM include, for example, depression ROM, contact ROM, OR type ROM by ion implantation, etc., and row decoders and row decoders with circuits and characteristics corresponding to these formats are used. Column decoders and sense amplifiers are used.

Further, the format of the ROM used in a one-chip microcomputer with a built-in EPROM is usually an OR type ROM, and the row decoder, column decoder, and sense amplifier also have circuits and characteristics corresponding to these. Further E
PRO? A write circuit, a control circuit, and the like are additionally required in the I-internal type microcomputer, which is unique to this microcomputer.

[Problem to be solved by the invention]

Therefore, a one-chip microcomputer with a built-in mask ROM and a one-chip microcomputer with a built-in EPROM naturally have different layouts and sizes, and in the manufacturing process, for example, all photomasks are manufactured individually. There were major problems in terms of development time and cost.

In addition, from the viewpoint of compatibility, of course, the mask ROM built-in type and the EP
RO - between built-in microcomputers
However, as mentioned above, it is difficult to make the electrical characteristics the same when the layout sizes of the chips are different.

Figure 7 is a layout diagram of a conventional one-chip microcomputer with built-in EPROM, and Figure 8 is also a mask R.
O? 'l This is a layout diagram of a built-in one-chip microcomputer. In Figures 7 and 8, 1.11 is a memory array area, 2.12 is a row decoder area, and 3.13 is a layout diagram of a built-in one-chip microcomputer.
indicate areas including column decoders and sense amplifiers, respectively.

As is clear from this figure, the mask ROM built-in type and the EP
It can be seen that there are differences in the layout and size of the one-chip microcomputer and the ROM built-in type.

The present invention was made in view of the above circumstances, and its purpose is to reduce the development period when developing either a one-chip microcomputer with a built-in EPROM or a built-in mask ROM.

To provide a method for manufacturing a one-chip microcomputer that can significantly reduce development costs and make the electrical characteristics the same.

[Means to solve the problem]

The method for manufacturing a one-chip microcomputer according to the present invention includes a photomask or photomask data used in the manufacturing process of a one-chip microcomputer with a built-in mask ROM and a built-in EPROM type, except for some steps. Photo mask.

Or share photomask data.

[Effect]

According to the present invention, it is possible to unify the chip layout size and unify the electrical characteristics.

〔Example〕

The present invention will be specifically explained below based on the drawings. 1st
Figure (a) is a layout diagram of a one-chip microcomputer with a built-in EPROM manufactured by the method of the present invention, and Figure 1 (b) is a layout of a one-chip microcomputer with a built-in mask of 120M manufactured by the method of the present invention. In the figure, 1.11 indicates a memory array area, 2.12' indicates a row decoder area, and 3.13' indicates a row decoder and sense amplifier area. EPROM
The manufacturing process of the built-in one-chip microcomputer is the same as the conventional process, while the mask R
The format of the built-in mask ROM in a one-chip microcomputer with a built-in OM is the format normally used in a one-chip microcomputer with a built-in EPROM, such as O.
In accordance with the R-type ROM, the chip layout and size are also the same as those of a one-chip microcomputer with a built-in EPROM, with the same basic circuit configuration as shown in Figures 2 (a) and (b). In the manufacturing process, E
The photomask for photolithography used in the manufacture of the one-chip microcomputer with a built-in PROM, or the data for the photomask (CAD data, etc.), except for a part, is also used.

Figure 2 (a) shows an EI'ROM manufactured by the method of the present invention.
Partial circuit diagram of the 3-row decoder area of the memory array area in a built-in one-chip microcomputer, Figure 2 (
B) shows a partial circuit diagram of a one-row decoder area of a memory array area in a one-chip microcomputer with a built-in mask ROM manufactured by the method of the present invention.

In the figure, Q, , Q indicate N-channel transistors for pill selection, respectively. Each N-channel transistor Q
! , Q3 respectively connect their gates to the column decoder output signal line Y
l+ connected to Yg and also connected to N-channel transistor t
The drain D of xt is connected to the sense amplifier 4.14, the source S is connected to the drain D of the N-channel transistor Q, and the source S of the N-channel transistor Q is connected to the memory cell transistors in the memory array areas 1 and 11. There is.

As shown in Figure 2 (A), the memory array area 1 of an EPROM internal + i-type one-chip microcomputer consists of an EPR with a floating gate structure.
It is composed of OM memory cell transistors, and R1
+ to R1 indicate memory cell transistors connected to the same bit line. Each memory cell transistor R1
1 to R1, whose gates are connected to the row decoder output signal line Lx
x, respectively, and their drains are connected to the same bit line.

On the other hand, the memory array area 11 in a one-chip microcomputer with a built-in mask ROM is composed of N-channel transistors, as shown in FIG.
u I I- (111 indicates memory cell transistors connected to the same pinpoint line.

As shown in FIGS. 2(a) and 2(b), the basic circuit configurations have the same layout and size.

This makes it possible to share the photomask and photomask data except for some steps in the manufacturing processes of both.

FIG. 3 is an explanatory diagram showing the manufacturing process of a one-chip microcomputer with a built-in EPROM type and a built-in mask ROM type. In the first gate formation process and the memory gate formation process, the photomask used for manufacturing the EPROM is a mask ROM. Except for the fact that it is not used in the manufacturing of the peripheral gate, and that separate photomasks are used in the peripheral gate formation process, other processes are used, such as island formation process, field formation process, isolation process, channel doping process, source・Drain formation process, contact hole formation process.

This means that the photomask can be substantially shared in the aluminum wiring formation process and the glass coat formation process.

Of course, the above manufacturing process is just an example, and it goes without saying that if other manufacturing processes are used, the photomasks and photomask data that can be shared will be different.

As a result, circuits that are unique to EPROM one-chip microcomputers, such as write circuits and control circuits, that are not present in mask ROM built-in one-chip microcomputers, are also formed in mask ROM built-in one-chip microcomputers. It will be done. However, these are not substantially used, and their presence does not cause any inconvenience to other circuits.

By the way, the current-voltage characteristics of an OR-type mask ROM memory cell and the current-voltage characteristics of an OR-type EPROM memory cell are as shown in FIG.

FIG. 4 shows the drain voltage on the horizontal axis and the current on the vertical axis. It is clear from this graph that < EPRO
Since the M memory cell has a floating gate and has a two-layer polysilicon structure, the current is smaller than that of an OR type mask ROM memory cell if the channel length and channel width are the same shape.

Therefore, the characteristics of the sense amplifier are changed in order to obtain the same electrical characteristics as a ROM when built into a one-chip microcomputer. Specifically, the intelligence of the sense amplifier is changed simply by changing the geometric shape of the transistor, for example.

For example, the area of the gate of the transistor 5 used for detecting the memory cell current in the sense amplifier is changed.

FIG. 5 is a circuit diagram of a part of the sense amplifier, which is used to detect the magnitude or magnitude of the current that changes depending on the input or non-input of a signal to the floating gate structure memory cell transistor Q in this circuit. The gate of the transistor shown in FIG. 6 is changed as shown in FIG.

Figure 6 (a) shows the transistor O5 used for current detection in the sense amplifier in a one-chip microcomputer with a built-in EPROM, and Figure 6 (b) shows the sense of transistor O5 in a one-chip microcomputer with a built-in mask ROM. The figure shows a schematic plan view showing each part of a similar transistor used in an amplifier. Figure 6 (
Although it is wide as shown in FIG. 6(b), it is narrow in the mask ROM built-in type as shown in FIG. 6(b). This makes it possible to eliminate the difference in characteristics between both memory cells shown in FIG.

Of course, such a change is just an example, and it goes without saying that the transistors to be changed and the number thereof are appropriately determined depending on the current characteristics of the sense amplifiers of both one-chip microcomputers or the manufacturing process thereof.

〔Effect of the invention〕

As mentioned above, in the method of the present invention, the EPROM built-in type,
In the process of manufacturing a one-chip microcomputer with a built-in mask ROM, some processes are excluded (because the photomask or photomask data is shared in other processes, the time and cost required for development are reduced. The present invention has excellent effects, such as making it possible to significantly reduce the amount of electricity used, and improving the uniformity of electrical characteristics between the two, thereby increasing compatibility.

[Brief explanation of drawings]

FIG. 1(a) is a chip layout diagram of a one-chip microcomputer with a built-in EPROM obtained by the method of the present invention, and FIG. 1(b) is a diagram of the mask ROM obtained by the method of the present invention.
Figure 2 (a), a chip layout diagram of an i-type one-chip microcomputer, is an EPR obtained by the method of the present invention.
Partial circuit diagram of the column decoder and sense amplifier section of a one-chip microcomputer with built-in OM, FIG. Circuit diagram, FIG. 3 is a main process diagram in the method of the present invention,
Figure 4 shows HPROM memory cells and OR type mask ROM.
5 is a partial circuit diagram of a sense amplifier, FIG. b) is a mask ROM
A schematic plan view showing some of the sense amplifier transistors in a built-in one-chip microcomputer, Fig. 7 is a layout diagram of a conventional EPROM built-in one-chip microcomputer, and Fig. 8 is the same (conventional mask ROM built-in). 1 is a layout diagram of a type one-chip microcomputer. 1...Memory array area 2...Row decoder area 3
Column decoder and sense amplifier area 4... Sense amplifier 11... Memory array area 12... Row decoder area 13... Column decoder and sense amplifier area 14... Sense amplifier R11-R1,. ...Memory cell transistor Ql, ~
Ql, . . . memory cell transistor In the drawings, the same reference numerals indicate the same or corresponding parts. Porridge diagram

Claims (1)

[Claims] (1) In the process of manufacturing a one-chip microcomputer with a built-in mask ROM and a one-chip microcomputer with a built-in EPROM, a plurality of photomasks for photolithography or photomask data are shared. A method for manufacturing a one-chip microcomputer.