JPS63244497A - semiconductor equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a semiconductor device, and in particular to a ROM (Read On) that can be user programmed according to customer wishes.
The invention relates to semiconductor devices such as microcomputers that include ly memory.

BACKGROUND OF THE INVENTION Conventionally, in consumer microcomputers and similar technologies, it has been common practice to transfer a customer's program onto a semiconductor memory device to realize desired desired functions. In recent years, due to the intensification of competition in technological development, the lifespan of products has become shorter and shorter, and the speed of development has become the most important factor for customers when selecting microcomputers.

However, although there are various mask ROM technologies for microcomputers (hereinafter abbreviated as MP) with user programs based on conventional customer requests, all of them are expensive or take a long time to deliver. becomes too long to meet the speed requirements. In other words, there is neither a solution that achieves both cost and development speed nor has it been proposed.

OBJECTS OF THE INVENTION An object of the present invention is to provide a semiconductor device that can realize required programming in a short time at low cost.

20 Structure of the Invention That is, the present invention provides a semiconductor device having a mask ROM section, in which the mask ROM section includes a first mask ROM programmable by an impurity diffusion pattern or an ion implantation pattern, an impurity diffusion region and a bit. The present invention relates to a semiconductor device comprising a second mask ROM which can be programmed by a wiring pattern between lines.

E, Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 schematically shows an MP (user program microcomputer) according to this embodiment.

In this MP, a CPU (Central Processing Unit), RAM (Random Access
sMemory) T/○ (input/output circuit), etc., and a mask ROM section 2 which is controlled by a PC (program counter) is provided.

The mask ROM section 2 consists of a main ROM 3 (described later) in which the main program can be changed, and a metal ROM 4 (described later) in which parameters can be easily changed. For example, in the case of an 8-bit MP design, assume that the memory portion occupies half of the chip. Metal ROM is preferable to achieve the shortest delivery time, but if the parameter change part requested by the user is 256 bits, by making only this part a metal ROM, it is possible to convert all ROMs to metal ROM. The chip cost can be reduced by about 50% compared to the conventional method.

To explain this in detail next, the mote ROM3 mentioned above is
As shown in FIG. 3, polysilicon gates (word lines) Wl, W2 are formed by impurity diffusion regions 5 indicated by diagonal lines in the figure.
, W3...... to form each transistor (the broken line 6 in the figure indicates one cell, and 7 to the bit lines B1, B2, B3...... contact area). In such a ROM 3, transistors are formed only at the positions where the impurity diffusion regions 5 are formed by the mask pattern, and the intended program is written. Therefore, programming according to user requests is performed by an impurity diffusion process at a relatively early stage of the device manufacturing process.
Although it takes a long time from receiving an order from a user to delivering the product (usually, for example, 30 to 50 days), the cell size is very small, and ROM pattern formation using a ratio controller is similar to that of other ROMs.

On the other hand, the above-mentioned metal ROM 4 is constructed as shown in FIG. Program whether or not to connect the drain to bit line B using the bit line B (wiring). That is, when a connection is made with the metal wiring 10, a transistor is formed, but when it is not connected (the drain is in an electrically floating state), the transistor is formed. It only takes 4 days (however,
The cell size is about twice that of the mote ROM. ), if you use a laser processing device etc., it is possible to change the program even after the process is completed. It is also possible to form a pattern in several hours by forming all metal ROMs in a connected state, cutting the required portions using the laser processing device described above, and programming.

In this way, the mask ROM part is connected to MO FROM and metal R.
By combining OM, as summarized in the following table, it is possible to achieve a significant development speed for new program changes such as parameter changes with almost no increase in cost.

In addition, in this embodiment, as mentioned above, in most consumer devices where development speed is required, the parameter data stored in a part of the program due to user requests etc. However, by using a subroutine, this can be easily assembled into a part of the user ROM as shown in FIG.
Among (2) in the figure, the metal ROM 4 can especially have a part that is easy to change, such as parameters. Moreover, changing the main program is a low-cost method)
Since it can be realized with M3 (of course, it is also possible with metal ROM), it is very advantageous in terms of cost.

For example, the proportion of the metal ROM4 differs depending on the purpose, but it is usually good to set it to 5 to 50% of the entire ROM'lf.

Contrary to the above, if other programming techniques were used, such as programming with or without contact holes, the cell size would increase and the delivery time would be shorter than that of metal ROM.
inferior to Furthermore, the method of changing the threshold voltage of a transistor by implanting impurity ions instead of using a moat ROM requires a long delivery time and is difficult to optimize process conditions. Also,
When programming with EPROM, EP to MP
It is not optimal as a mass-produced model for consumer use due to the increased cost of integrating ROM, technical difficulties, packaging, data retention characteristics, shipping evaluation, etc. Furthermore, EEPROM programming presents the greatest technical difficulty and the largest cell size, which limits the range of applications.

In this way, none of the programming methods is optimal in terms of cost, speed, or technical difficulty, and there are cases where customers rely on expensive and difficult programming techniques at the expense of cost due to demands for faster delivery times. By using the apparatus of this embodiment, 2 to 4
This means that delivery can be achieved at the speed of a few days, and it is possible to provide an extremely advantageous and highly effective MP.

Although the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

For example, the mask ROM part is a mode ROM and a metal ROM.
In addition to the configuration, other programming elements (for example, those that program based on the presence or absence of contact holes) can also be used in combination. Further, the MP may also have a layout other than the above-mentioned layout.

6. Effects of the Invention As described above, the present invention can minimize the cell size (i.e., reduce costs) by using the first mask ROM, while increasing the development speed by using the second mask ROM, thereby reducing costs. It is possible to realize required programming while satisfying both speed and speed at the same time.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which FIG. 1 is a schematic layout diagram of an example of a microcomputer with a user program, FIG. 2 is an example of the existence of parameter data (FIG. 2(a)),
Figure 3 (A) is a plan view of the main parts of the mote ROM, Figure 3 (B) shows its aggregation (Figure 3 (b)).
) is its equivalent circuit diagram, Figure 4 (A) is a plan view of the main part of the metal ROM, and Figure 4 (B) is the equivalent circuit diagram.
) is its equivalent circuit diagram. In addition, in the symbols shown in the drawings, 1......Microcomputer 2...
......Mask ROM section 3...Moat ROM 4...Metal ROM 5.15...Impurity diffusion region 6.16・
. . . Memory cell 10 . . . Metal wiring.

Claims (1)

[Claims] 1. In a semiconductor device having a mask ROM section, the mask ROM section is programmable by a first mask ROM which is programmable by an impurity diffusion pattern or an ion implantation pattern, and a wiring pattern between the impurity diffusion region and the bit line. A semiconductor device comprising a second mask ROM.